1. Field of the Invention
The present invention relates to a device for injection of a sterile and antipyrogenic fluid obtained by filtration, and to a method for checking the integrity of the filter used for this purpose.
2. Description of the Related Art
The injection device according to the invention is of the type that includes: at least one filter having a first and a second compartment which are separated by a porous membrane, the first compartment having an inlet which can be connected to a source of fluid to be filtered, and the second compartment having an outlet connected to an injection channel; means for circulating the fluid through the filter and into the injection channel; and means for checking the integrity of the filter.
Such a device is described in the patent U.S. Pat. No. 4,702,829, in combination with a haemodiafiltration installation. In this device, the first compartment of a first filter is equipped with a vent insulated from the atmosphere by a hydrophobic microfilter, and it is connected, by way of a second filter, to a supply channel of a dialysis circuit. During operation, the injection channel is connected to a bubble trap of a purified blood return channel which is linked to a patient.
The integrity of the filters is checked outside the operating periods of the installation. To do this, the dialyser is removed from the dialysis fluid circuit, and the dialysis fluid circuit is linked up in such a way as to form a closed circuit. Also, the injection channel is connected to the dialysis fluid circuit. Dialysis fluid is then pumped from the dialysis fluid circuit, whereby air enters through the vent of the first filter into the compartments of the filters which are in communication. Dialysis fluid is pumped until the compartments of the filters which are in communication are filled with air and until a defined subpressure is created in the circuit. The pressure in the circuit is measured: if the membranes are intact, air can not pass through them and the pressure remains constant.
This method for checking the integrity of the filters has the disadvantage that it can only be used outside the treatment sessions. Furthermore, it requires the use of a particular filter having a first compartment equipped with a vent insulated from the atmosphere by a hydrophobic microfilter.
The object of the invention is to provide an injection device of the type mentioned above, the filter of which can be checked during use.